When two systems communicate, a device or an identity using a device in one of the computer systems typically is identified to the other computer system. In some computer systems, the identity of a user or a device must be authenticated before the user or the device is permitted to access functions provided by the computer system. User authentication may be based on the presentation of a user name and a password, the combination of which is validated by the computer system. Also, a user or a device may be authenticated using a cryptographic process in which a user identity or a device is proven valid through the use of cryptographic authentication credentials.